feat: v0.2.1 — reference links, context menu, RTL, ja/ko, regex search, hooks, copy API

## Added
- Reference link/image resolution: [text][ref] + ![alt][ref] with [ref]: url definitions
- Right-click context menu: undo/redo/cut/copy/paste/selectAll + custom items
- RTL CSS layout support for Arabic, Hebrew, Persian etc.
- Japanese (ja) and Korean (ko) locales with 60+ keys each
- Divider position localStorage persistence
- Regex search toggle in search/replace panel
- Export HTML with embedded CSS styles
- beforeChange / afterChange lifecycle hooks (instance + global)
- copyAsMarkdown() / copyAsHTML() clipboard APIs
- CHANGELOG.md, CONTRIBUTING.md, CI workflow (.github/workflows/ci.yml)
- 2 new test suites: index.test.ts, styles.test.ts (684 total tests, +74)

## Changed
- autoSave plugin: closure-based state per instance instead of this context
- Plugin install() now receives options as second argument
- RTL locale detection: now uses language prefix (ar-SA → RTL)
- Rollup dev mode: only builds UMD format
- prepublishOnly now includes typecheck + test
- Version bumped to 0.2.1

## Fixed
- [text][ref] now correctly renders as link (was raw text)
- ![alt][ref] no longer produces empty src
- autoSave plugin state isolation across multiple editor instances
- Footnote definitions no longer consumed by refDef handler

site/index.html

@@ -4,7 +4,7 @@
 <meta charset="UTF-8"/>
 <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
 <link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>🚀</text></svg>"/>
-<title>MetonaEditor v0.2.0 · TypeScript · 桌面端 Markdown 编辑器</title>
+<title>MetonaEditor v0.2.1 · TypeScript · 桌面端 Markdown 编辑器</title>
 <style>
 *{box-sizing:border-box;margin:0;padding:0}
 :root{--bg:#0f1117;--bg-soft:#161922;--card:#1c2029;--card-hover:#232834;--text:#e6e8eb;--muted:#9ca3af;--accent:#3b82f6;--accent-2:#8b5cf6;--accent-3:#ec4899;--accent-soft:rgba(59,130,246,.12);--border:rgba(255,255,255,.08);--gradient:linear-gradient(135deg,#3b82f6 0%,#8b5cf6 50%,#ec4899 100%);--shadow:0 20px 50px -20px rgba(0,0,0,.5)}
@@ -106,10 +106,10 @@ footer a:hover{text-decoration:underline}
   <h1>TypeScript 重构 · 零依赖<br/><span class="grad">桌面端 Markdown 编辑器</span></h1>
   <p class="tagline">全模块 TypeScript 严格模式，内置自研解析器（99% 行覆盖率），6 个预设插件，中文优先。为桌面端现代 Web 应用而生。</p>
   <div class="badges">
-    <span class="badge accent">v0.2.0</span>
+    <span class="badge accent">v0.2.1</span>
     <span class="badge">TypeScript</span>
     <span class="badge">零运行时依赖</span>
-    <span class="badge">610 tests</span>
+    <span class="badge">684 tests</span>
     <span class="badge">桌面端优先</span>
     <span class="badge">MIT</span>
   </div>
@@ -120,7 +120,7 @@ footer a:hover{text-decoration:underline}
   <div class="stats">
     <div class="stat"><div class="stat-num">0</div><div class="stat-label">运行时依赖</div></div>
     <div class="stat"><div class="stat-num">99%</div><div class="stat-label">解析器行覆盖</div></div>
-    <div class="stat"><div class="stat-num">610</div><div class="stat-label">单元测试</div></div>
+    <div class="stat"><div class="stat-num">684</div><div class="stat-label">单元测试</div></div>
     <div class="stat"><div class="stat-num">~30KB</div><div class="stat-label">gzip 体积</div></div>
   </div>
 </header>
@@ -214,7 +214,7 @@ editor<span class="c-punc">.</span><span class="c-fn">exec</span><span class="c-
       <a href="https://git.metona.cn/MetonaTeam/MetonaEditor" target="_blank" rel="noopener">源码仓库</a>
       <a href="https://git.metona.cn/MetonaTeam/MetonaEditor/issues" target="_blank" rel="noopener">问题反馈</a>
     </div>
-    <div>MetonaEditor v0.2.0 · TypeScript · MIT License · MetonaTeam</div>
+    <div>MetonaEditor v0.2.1 · TypeScript · MIT License · MetonaTeam</div>
   </div>
 </footer>
 
@@ -224,7 +224,7 @@ MeEditor.themes.switchTheme('dark');
 MeEditor.create('#editor', {
   mode: 'split', height: 480, theme: 'dark',
   value: [
-    '# 欢迎使用 MetonaEditor v0.2.0',
+    '# 欢迎使用 MetonaEditor v0.2.1',
     '',
     '一个 **TypeScript 重构 · 零运行时依赖** 的桌面端 Markdown 编辑器。',
     '',